US Bridges

Il 31 over US 20 by Pass

Poor

Kane County, Illinois · 3 M S of I-90 · Structure no. 045001700000000

Built
1959
66 years old
Condition
Poor
inspected January 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
72 ft
1 main span
Daily traffic
15,800
2023 count
Owner
State
State Highway Agency

About this bridge

Il 31 over US 20 by Pass is a steel stringer/multi-beam or girder carrying Il 31 over US 20 by Pass in Kane County, Illinois. It was built in 1959, so it is 66 years old, older than the Illinois average of 45.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

It carries about 15,800 vehicles a day, roughly 9% of them trucks, projected to reach 12,688 by 2046. The structure is 72 ft (21.9 m) long and 70 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesIl 31
CrossesUS 20 by Pass
Location3 M S of I-90
RouteState Highway 31
CountyKane County
StateIllinois
Coordinates42.0219, -88.28347
Functional classUrban Minor Arterial

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Deck4 PoorAdvanced section loss, deterioration, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Last inspectionJanuary 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating91.4 US tons
Inventory rating56.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length72 ft (21.9 m)
Longest span67 ft (20.5 m)
Deck width70 ft (21.3 m)
Roadway width55 ft (16.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic15,800 (2023)
Projected traffic12,688 by 2046
Trucks9%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
Detour if closed1.9 mi (3 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was Il 31 over US 20 by Pass built?

It was built in 1959, making it 66 years old in 2025.

What condition is Il 31 over US 20 by Pass in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in January 2024.

How much traffic does Il 31 over US 20 by Pass carry?

About 15,800 vehicles per day (2023 count), of which roughly 9% are trucks.

How long is Il 31 over US 20 by Pass?

The structure is 72 ft (21.9 m) long with a longest span of 67 ft (20.5 m) and a deck 70 ft wide.

Who owns Il 31 over US 20 by Pass?

It is owned by the State Highway Agency.